Vehicle provided with endless or self-laying tracks



Oct. 18, 1938. D. R. BOMFORD El AL VEHICLE PROVIDED WITH ENDLESS ORSELELAYING TRACKS Filed May 20, 1957 2 Sheets-Sheet l Oct. 18, 1938. D.R. BOMFORD ET AL 2,133,653

VEHICLE PROVIDED WITH ENDLESS OR SELF LAYING TRACKS Filed May 20, 1937 2Sheets-Sheet 2 1 7g. 5. 1 19.6.

a 5 76 /6 m [60 I5 /5 L V l +6 77 .W/ e M0 1 m w; m M

Patented Oct. 18, 1938 UNITED STATES PATENT OFFICE VEHICLE PROVIDED WITHENDLESS OR SELF-LAYING TRACKS Application May 20,

1937, Serial No. 143,824

In Great Britain November 21, 1936 1 Claim.

This invention relates to tractors and other vehicles provided with whatare technically known as endless-tracks" or alternatively as self-layingtracks, the term endless-tracks being hereinafter used for preference.

The invention is more particularly concerned with the construction ofthe tracks for such vehicles, which tracks as is well understoodordinarily embody a series of plate-like members,

commonly termed tread-plates, mounted on and carried by substantiallyinextensible metallic bands or cables the respective ends of which arebrought together and interconnected to form loop-like members which withthe tread plates mounted thereon constitute an endless track one end ofwhich passes over a sprocket wheel adapted to co-act with a part on thetread plates for effecting the travelling motion of the track over thesaid sprocket and over an idle or guiding wheel over which the other endof the endless track passes, a small roller or a plurality of suchrollers being usually provided to bear on the track intermediate thedriving sprocket and the idle or guiding wheel in a manner and for thepurpose well understood.

This invention has for its object to provide endless-track mechanism fortractors and other vehicles, more simple in construction and efflcientin operation than endless-track mechanisms as heretofore constructed.

The present invention is characterised in that the endless trackembodies a series of tread plates of channel-like formation each treadplate having in combination therewith means whereby it may be directlyclamped to a plurality of stranded wire or like flexible members inlooplike form, the clamping means provided constituting a projection onthe said plates for the engagement therewith of the teeth or equivalentparts of the driving wheel, the said clamping means also being sodesigned that the portions of the cables intermediate the parts whereonthe successive tread plates are clamped are permitted to assume, whenthe said tread plates are passing over the driving wheel and the idle orguide wheel, a curvature substantially conforming to that of the saidwheels, whereby wear on the parts of the cables adjoining the partsengaged by the clamping means is reduced to a minimum.

The invention further resides in certain details of construction to behereinafter more particu larly referred to and illustrated by theaccompanying drawings with reference to which the invention will now bedescribed.

Figure 1 of the drawings represents, more or less diagrammatically inside elevation, an endless track in accordance with the invention theco-acting wheels only of the tractor or vehicle to which the track isapplied being shown in the said figure, and it will be appreciated thatthese tracks are, as usual, provided at both sides of the vehicle.

Figure 2 is a plan view showing one of the tread plate membersseparately with parts of the cables to which it is attached.

Figures 3 and 4 respectively represent sections of the same on theplanes indicated by the dotted lines 3-3 and 4-4 in the said Figure 2.

Figures 5 and 6 are similar views to Figures 3 and 4 illustrating aconvenient method for effecting the anchorage of the free ends of theflexible cables to one of the tread plates.

Figure 7 is a view showing in longitudinal section a portion of thetrack and a fragmentary part of a driving wheel of a constructionhereinafter more particularly described, which may be used on vehiclesprovided with tracks in accordance with this invention.

Figure 8 is a transverse section on the plane indicated by the dottedline 8-8, Figure 7.

Figures 9 and 10, represent in plan and sectional side elevationrespectively, a modified construction of the clamping member hereinaftermore particularly referred to.

' In the said Figure 1 of the drawings the reference numbers II and I2respectively denote a driving sprocket, which may be of the constructionhereinafter more particularly described, and a guide wheel over whichthe endless track, embodying a series of tread plates which are denotedgenerally by the reference I3, is adapted to travel in the operation ofthe tractor or the like furnished with the said endless track while Idenotes a loading roller adapted to act on the track at a part thereofintermediate the said driving and guide wheels II and I2.

In the convenient embodiment of the invention illustrated the treadplates I3 are mounted directly on and carried by a pair of flexiblemetallic cables ii, the said cables being preferably of stranded wireand being spaced apart in parallel planes 8. sufficient distance topermit the teeth or equivalent parts of the driving sprocket l I to workbetween them.

Each of the tread plates 13, which plates have side flanges l3 whichgive them a channel-like formation, has in conjunction therewith meansfor effecting its attachment directly to the cables I! the said meanscomprising two blocks, marked l6 and I6- respectively which co-act toprovide on the inner face of the bottom of thechannellike tread plate abearing and clamp wherein those portions of the parallel cables I!whereon each tread plate is located are adapted to be securely gripped.

The block it, which is hereinafter referred to as the inner block, maybe formed integral with the channel-like tread plate I3 or it may bemade separate therefrom and if desired welded or otherwise secured tothe inner face thereof and the said block is of such width in thetransverse direction of the plate as to leave sufllcient space betweenthe longitudinal sides of the block and the inner faces of the channelsides I3 to permit the passage between them of the peripheral parts ofthe driving wheel II, guiding wheel l2 and loading roller II.

The upper face of this inner block I8 is furnished with twolongitudinally extending parallel grooves l6 of substantiallysemi-circular figure in cross section and spaced apart at the requisitedistance to receive the flexible cables IS.

The block I6 which co-acts with the said inner block l6" to constitutethe bearing and clamp for the cables, which block I6 is hereinafterreferred to as the outer block, has in the inner face of the partthereof which is located on the inner block grooves |6 coinciding withthe grooves l6 in the upper face of the inner block and the said outerblock "5 is furnished at or adjacent each corner thereof with alongitudinally directed projection lG into and along which the saidgrooves l6 in itsinner face extend. The grooves |6 in the portionsthereof which extend into and along the said projections Hi on the outerblock are given such a curvature as will permit the portions of thecables whereover the said projections I6 are located to conform, whenthe tread plates of the track are passing over the sprocket andsupporting wheels II and I2, to the curvature or substantially to thecurvature of the said wheels, the curved extensions of the grooves l6acting to prevent wear on the cables at the parts adjacent the portionsgripped between the clamping blocks.

Where the extensions l6 are made separate from the block l6 they may beformed from suitably shaped pieces of bar metal which may be secured tothe blocks by welding or otherwise secured thereto and when they areformed integral with the block the said block is made by casting, thecasting having the form shown in plan in Figure 9 and sectional sideelevation in Figure 10 of the drawings.

The outer block I6 is drawn into the clamping position on the cables l5by a screw bolt, or preferably a plurality of screw bolts ll, which maybe passed upwardly through holes provided in the bottom of the treadplate l3 and coincident bores in the inner block Hi their screwed endstaking into tapped holes provided for their reception in the outer blockHi.

The free ends of the flexible cables l5 may be anchored to a shoe ortread plate l3 which, as is illustrated by Figures 5 and 6, is providedwith co-acting clamping blocks I 6 and I6 each having two pairs ofgrooves marked respectively l6'- and li in their presented faces inwhich grooves the respective ends of the cables l5 can be laid inoverlapping relationship, the cable ends projecting beyond the ends ofthe inner block l6 and having ferrules i5 fixed thereon which ferruleswhen the outer block I6 is secured in place prevent the cable ends beingdrawn from the clamp by any longitudinal strain thereon.

The sprocket or driving wheel may be furnished with tooth-like partssuitably shaped for engaging with the clamping members I, I! describedand having a width which will permit them to pass between the cornerlugs or projections It on the outer block I 6 into the necessaryengagement.

Or in lieu of employing a driving wheel having tooth-like parts forco-acting with the projections on the tread plates formed by theclamping blocks I, li the said driving wheel may be constituted as isshown in the drawings by a pair of parallel circular plates Ilspacedapart and connected to each other by a series of pins ll which extendhorizontally and at equi-distant points around and between the presentedfaces oi. the discs II- and provide spindles for rollers ll which act onthe projections formed by the cable clamping means on the tread platesto eifect the travelling motion of the endless track.

The guiding wheel l2 and bearing roller ll are formed by spaced apartdiscs or otherwise so formed that their peripheries can occupy thespaces between the sides ll of the tread plates and the projectionsformed by the clamping means for the cables, and bear against thebottoms of the said tread plates.

The transverse rear edges of the tread plates, regarded in relation tothe direction in which they travel, are preferably slightly cranked asshown at I I so that the said edges may overhang the forward edge of thenext succeeding tread plate and the parts thus cranked may have on theirouter faces an outwardly projecting transverse rib ll, the said ribsacting as tynes.

It is to be understood that we do not limit ourselves to the employmentof two flexible cables only as the number of such cables employed in theconstruction of the track may be increased if desired and further inlieu of wire cables narrow bands of spring steel or laminations thereofmay be employed, the cross sectional shape of the grooves I6 and It inthe clamping members l6 and I6 respectively being modified accordingly.

We claim:-

An endless track for tractors and other vehicles adapted for endlesstrack propulsion the said track embodying in combination a plurality offlexible metallic members of endless loop-like formation, a series oftread plates of channel-like form in transverse section and disposed incontiguity and cross-wise on the said flexible endless loop-likemembers, each tread plate having in conjunction therewith an outer blocklongitudinally grooved to provide seatings for the portions of theflexible members on which the tread plate is located and an inner blockcorrespondingly grooved and coacting with the outer block to clamp t etread plate to the flexible members, the sai outer block being providedat or adjacent the corners thereof with longitudinally directedprojections which overhang portions of the flexible members intermediatethe parts to which successive tread plates are clamped, the grooves inthe said outer block extending into these longitudinal projections andthe parts of the said grooves in the projections being so curved as topermit the parts of the flexible members over which the projectionsextend to assume a curvature substantially conforming to that of thedriving wheel and guide wheel over which the track passes.

DOUGLAS RAYMOND BOMFORD. ERNEST RAYMOND BOMFORD.

